<template>
  <div class="spec-preview">
    <!-- 左侧图 -->
    <img :src="imgObj.imgUrl" />
    <!-- 鼠标移动的位置 -->
    <div class="event" @mousemove="moveHander"></div>
    <!-- 右侧放大图 -->
    <div class="big">
      <img :src="imgObj.imgUrl" ref='big'/>
    </div>
    <!-- 遮罩层 -->
    <div class="mask" ref='mask'></div>
  </div>
</template>

<script>
  export default {
    name: "Zoom",
    props:{
      skuImageList: {
        type: Array,
        default: () => []
      }
    },
    computed:{
      imgObj(){
        return this.skuImageList[this.curIndex] || {}
      }
    },
    data(){
      return{
        curIndex:0
      }
    },
    mounted(){
      this.$bus.$on('getIndex',(index)=>{
        this.curIndex = index
      })
    },
    methods:{
      moveHander(event){
        let big =  this.$refs.big
        let mask = this.$refs.mask
        let leftX = event.offsetX - mask.offsetWidth/2
        let topY = event.offsetY - mask.offsetHeight/2
        if(leftX <= 0){
          leftX = 0
        }
        if(topY <= 0){
          topY = 0
        }
        if(leftX >= mask.offsetWidth){
          leftX = mask.offsetWidth
        }
        if(topY >= mask.offsetHeight){
          topY = mask.offsetHeight
        }
        mask.style.left = leftX + 'px'
        mask.style.top = topY + 'px'
        big.style.left = -2*leftX + 'px'
        big.style.top = -2*topY + 'px'
      }

    }
  }
</script>

<style lang="scss">
  .spec-preview {
    position: relative;
    width: 400px;
    height: 400px;
    border: 1px solid #ccc;

    img {
      width: 100%;
      height: 100%;
    }

    .event {
      width: 100%;
      height: 100%;
      position: absolute;
      top: 0;
      left: 0;
      z-index: 998;
    }

    .mask {
      width: 50%;
      height: 50%;
      background-color: rgba(0, 255, 0, 0.3);
      position: absolute;
      left: 0;
      top: 0;
      display: none;
    }

    .big {
      width: 100%;
      height: 100%;
      position: absolute;
      top: -1px;
      left: 100%;
      border: 1px solid #aaa;
      overflow: hidden;
      z-index: 998;
      display: none;
      background: white;

      img {
        width: 200%;
        max-width: 200%;
        height: 200%;
        position: absolute;
        left: 0;
        top: 0;
      }
    }

    .event:hover~.mask,
    .event:hover~.big {
      display: block;
    }
  }
</style>